The gender pay gap is the difference between the median average hourly wage of men and women working in the same organisation.

It is not the same as equal pay, where firms are required by law to pay men and women doing the same job the same salary.

This is the second year that all organisations with at least 250 employees are required by law to report their gender pay gap.

This year, employers must publish data based on a snapshot of their workforce on March 31 2018 (public sector) or April 5 2018 (private and voluntary).

(PA Graphics)

So far, the new figures show that:

– Asda has reduced its gender pay gap year-on-year (from 8.9% to 7.6%) but Aldi has reported a rise (from 4.8% to 7.1%).

– Of the UK’s main broadcasters, the BBC, ITN and Channel 4 have reported their figures. The BBC has reduced its gender pay gap from 9.3% to 7.6%, ITN’s figure is down very slightly from 18.2% to 18.1%, and Channel 4 has reported a drop from 24.2% to 23.3%.

– Most government departments have reduced their gender pay gap, although it has increased at the Treasury and the departments for International Trade, International Development, Exiting the EU and Digital, Culture, Media & Sport (DCMS). The largest gap is at the DCMS (22.9%), the smallest at the Department for Education (5.6%), and there is no gap at all at the Department of Work and Pensions.

– Three of the big high street banks have seen their gap increase (Barclays, HSBC and RBS), two have reported a decrease (Santander and TSB) while the figure for Lloyds is unchanged. Barclays has the largest gap (44.1%) and TSB has the smallest (23.3%).

The median gender pay gap for all workers in the UK is 17.9%, according to the Office for National Statistics.

Of the 991 organisations who have published a comparable gender pay gap for both this year and last year, 398 (40%) have reported an increase, 56 (6%) no change and 537 (54%) a decrease.

The Equality and Human Rights Commission (EHRC), which enforces the gender pay gap legislation, said that in 2018 – the first year the regulations were introduced – 94% of organisations had published their data by the required deadline.

Following enforcement action by the EHRC against employers who were believed to be in breach of the rules, this had risen to 100% by August.